This invention relates to venting of gases from an apparatus. In particular, it relates to venting of gases which carry with them entrained particulate matter and/or entrained liquid mist.
Gases vented from an apparatus often contain entrained particulate matter and/or entrained liquid mist. The removal and collection of such entrained substances is desirable for several reasons. First, the entrained matter tends to accumulate around the passage restricting the area of the vent opening, necessitating periodic clean-ups which result in additional loss of productivity. Second, the removal and collection prevents pollution, and often eliminates an environmental-, safety- or health-hazard. Finally, the collection of the substance results in recovery of an often valuable product. It is economically preferable to automatically return the collected matter into the apparatus from which it escaped. Various devices have been proposed for collection and automatic return of the collected matter. One such device, used on an extruder vent, comprises a screw rotatably mounted and closely fitting inside a tubular vent passage. The rotating screw allows the gases to pass through, but it traps the entrained matter. The rotational direction and the screw pitch are such that the trapped material is returned into the extruder. In a variation of that concept, instead of a screw a rapidly reciprocating piston or ram is employed to trap the particulate matter and return it to the extruder. Another device, utilizes twin screw arrangement for trapping and returning the collected entrained matter while allowing the gases to pass through.
These devices, however, reduce the available passage area in the vent and thereby increase the velocity of the escaping gases. The increased velocity causes some of the entrained matter to pass through the collecting device. Furthermore, some of the entrained matter deposits in the entrance section of the vent in front of the working parts of the collecting device clogging the passage area.
The present invention obviates the problems encountered in the prior art.
Thus, one object of the invention is to provide an improved apparatus for collecting and returning matter and mist entrained in the gases escaping through a vent.
Another object of the invention is to eliminate environmental-, safety-, and health-hazard by removing entrained matter from gases escaping through a vent.
Still another object of the invention is to provide for removal of entrained matter by means of a device causing minimum increase in velocity of the escaping gases.
A further object of the invention is to provide for removal of entrained matter from gases without causing formation of deposits near the entrance to the vent, in front of working parts of the device for collecting and returning entrained matter.
A still further object of the invention is to prevent economic losses by returning substantially all entrained matter, collected from the escaping gases, to the apparatus.
Still another object of the invention is to return collected matter to the apparatus with minimum delay and without any interruption of the process carried on in the apparatus from which gases are vented.
A still further object of the invention is to provide an improved venting system for an extruder.
Still another object of the invention is to provide a venting system which allows for venting of gases in a uniform and continuous manner.
A still further object of the invention is to provide a venting system for an extruder which allows for collection and return of particulate matter and mist which are entrained in the escaping gases.
Still another object of the invention is to provide a venting system wherein the device for collecting and returning particulate matter and liquid mist entrained in the escaping gases is an only slightly modified commercially available device.
Other objects of the invention will become obvious to one skilled in the art upon reading of this specification and of the appended claims.